PPTP (Point to Point Tunneling Protocol) is a network technology for supporting multiprotocol virtual private network (VPN), which works on a second layer. Based on the PPTP protocol, a remote user can secure access to a corporate network via Microsoft Windows NT Workstation, Windows XP operating system, Windows 2000 operating system, Windows 2003 operating system, Windows7 operating system, and other systems installed with a point-to-point protocol. The remote user can dial into a local ISP, and securely link to the corporate network over the Internet.
The basic process of tunneling technology is that at an interface between a source LAN and a public network, data (e.g., data from the data link layer or the network layer in the seven-layer ISO/OSI model) as a payload is encapsulated in a data format that can be transmitted over the public network, and at an interface between a destination LAN and the public network, the payload can be taken out by de-encapsulating the data.
The VPN built by using the PPTP has relatively strong stability and security, and PPTP is also used by relatively mainstream VPN servers nowadays. There are multiple VPN access scenarios using PPTP, for example, employees who travel for work can use the VPN to access the enterprise internal network, and subsidiaries can use the VPN to access the parent enterprise internal network. However, this way of access has cross-regional and cross-carrier factors. The poor access quality and slow access speed make it difficult to meet the need of customer on access quality.
Currently, a relatively common agent system is shown in FIG. 1. A server 110 is arranged on a client-side router, which intercepts TCP (Transmission Control Protocol) traffic, and/or UDP (User Datagram Protocol) traffic, and the like. The intercepted traffic is forwarded to a nearest B server 120 via a dedicated high-speed network for back-to-the-source. Thereby, the access speed can be greatly enhanced. However, the agent system as shown in FIG. 1 does not support the GRE protocol (Generic Routing Encapsulation). Therefore, the agent system cannot accelerate the PPTP VPN traffic.